ILCDR/CesrTA meeting Low Emittance Tuning 報告

200807 K.Kubo

ILCDR08 workshop + CesrTA meeting

• 2008. 7.8 ~ 11 at Cornell

• Two topics:– Electron Cloud (main issue) 末次報告– Low emittance tuning 久保報告

• 参加者　 ~40 (E-cloud : LET ~ 2:1)–日本 (KEK)から７人

Mark Palmer & David Rubin

Mark Palmer & David Rubin

Mark Palmer & David Rubin

Low Emittance Tuning session

• Overview, A.Wolski• Experimental Plan for low emittance in CesrTA, David R

ubin• Talks on Instrumentation and measurement techniques• Reports of machine experiences and tuning methodes• Modeling and plans for future machines• Modeling and plans for CesrTA• Discussions, plans for CesrTA, Collaborations

Overview by A.Wolski

• Design issues of ILC DR– Low emittance, <=2 pm– Difficulties depend on design (no clear conclusion)

• The three-pronged approach:– Modeling and simulations– Instrumentation and diagnostics– Experience of existing machine

Experimental Plan for low emittance in CesrTA, David Rubin

• CesrTA lattice• Sensitivity of vertical emittance to optical and alignment

errors• Beam based alignment

– Beam position monitor upgrade

• Survey• Dispersion measurement and correction• Coupling measurement and correction• Beam size monitor• Lifetime as a measure of beam size• Schedule

Instrumentation and measurement techniques

• X-ray beam size monitor at ATF DR, H.Sakai (Tokyo U.)• Fast X-ray beam size monitor for CesrTA, J.Alexander

(Cornell U.)• High performance BPM, M.Wendt (FNAL)• AC dispersion measurement, D.Rubin (Cornell U.)• Beam based survey and alignemnt of magnets, D.Rubin

(Cornell U.)

Reports of machine experiences (tuning methods)

• Coupling correction at Australian Synchrotron, R.Dowd (ASP)

• PEP-II optics modeling and low emittance tuning, Y.Yan (SLAC)

• Orbit response matrix analysis at ATF, A.Wolski (Cockcroft/U.Liverpool)

• BBA at ATF, T.Okugi (KEK)• Optics correction at KEKB, K.Oide (KEK)

Modeling and plans for future machines

• NSLS-II Lattice design strategies, W.Guo (BNL)• Simulation of orbit and dispersion correction in ILC DR,

K.Panagiotidis (Cockcroft)

Modeling and plans for CesrTA

• Optics modeling, D.Sagan (CLASSE)• Optics correction, D.Sagan (CLASSE)• Beam Based Alignment of BPM with Orbit Response Mat

rix and coupling measurement, J.Shanks (CLASSE)

CLASSE: Cornell Laboratory for Accelerator Sciences and Education

R.Dowd (ASP)

Our calibrated model indicates we can currently achieve a verticalemittance of ~ 2-3 pm.rad

Betatron Phase & Coupling Measurement

Coupling and betatron phase and are measured by shaking the beam at a betatron resonance and looking at the response at the BPMs.

David SaganCornell University

y

x

y

x

y

x

y

x

General case: beam motion is elliptical

No coupling case

C12 0, C22 = 0

C12 = 0, C22 0

C12 ~yamp (out - of - phase)

xamp

C22 ~yamp (in - phase)

xamp

K.Oide

BPM has 4 electrodes.x,y,intensity can be solved from data of 3 electrodes.Can be used for gain calibration of the other electrode. Drift of electronics can be corrected.

For ATF, instrumentation• BPM performance is very important

– 20 BPMs were upgraded for test and the performance confirmed

– Remaining 76 BPMs ???• Calibration should be regularly performed

– Learn experience in KEKB (?) (man power)• Fast and accurate beam size monitor is important

– Real time monitor during tuning• Possible “new” methods

– AC measurement may be considered• Modulation of RF to induce synchrotron oscillation • Need turn by turn BPM

– Resonance excitation (betatron oscillation) may be considered• Need phase lock of exciter, turn by turn BPM

For ATF, tuning and correction• Optics should be cared.

– Beta-function beats are very large. Need to perform matching.

– Learn experiences of other rings.• Consider different COD, dispersion and Coupling

correction methods (?)

For ATF, alignment etc.• Magnet re-alignment will be done in this summer • Beam Based Alignment Measurement is important

– Qaud to BPM is straight forward– Sext to BPM ? – Consider other methods.

• Issues of skew quad– All sextpoles have skew quad trim coils.– Field quality has not been checked– Skew quad center is sext center ? (affect BBA)

For ATF Low emittance, SummaryLearn from other machines

Continuous

maintenance/

tuning/calibrations

are important

BP

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